Have you tried making a smart playlist to find anything recently added to your library? The track info retrieved from the Internet during the import might have been wrong, causing Disc 2 to be categorized as something else entirely. (I've had that happen before. Since I have a large library, I could not find the CD after import by just browsing through my album/artist list.)
What I've done is make a smart playlist with the criteria of Date added is in the last 1 days. (or whatever number of days you want)
If the CD has indeed been imported, it will be on that playlist. If it isn't there, then I'm not sure what the issue could be.